relays and air bag suspension

Ok, I haven't posted here in a while but I have a diagram I'm gonna try my best to explain it correctly.

I have an air bag suspension on my car and the guy I bought it from had it wired a certain way

Its (2) Viair Compressors 400C, 2 automotive relays, 7 gallon tank, 8 valves, pressure switch, 10 switch box, and 2 toggle switches

He had it wired to where you could flip the toggle switch mounted on the tank to cut the compressor on or off being that they drew alot of amperage.

So my question is: With the normal automotive Relay being:

30= power/12v positive     85=ground     86=load/signal wire from switch     87 and 87a= the "product" (fan, pump, fog lights, ect)

Where would the signal wire from the pressure sensor plug into, to tell the compessors to cut on? It was wired to where the toggle switches controlled which compressor or both were pumping so they wouldnt overheat.

So where does the signal wire from the pressure sensor go into the relay? does it splice into the positive compressor wire? into the load wire for the toggle switches? WHERE?

If the pressure switch is NC I would wire it between ground and pin 85.  That way, when the tanks are full the pressure switch will break the ground going to the relay, thus preventing it from working with or without the switch.

I guess it depends on how the pressure switch works though - is it a high pressure switch or a low pressure switch?

I would also use an ignition feed to power the switch that controls the relay so that the pumps won't run when the car is off.  Of course, if you do that, then you won't need the switches at all.

Yeah I need to get out there and test the pressure switch with a test light to see if the signal wire coming off it is a negative (dont see why it would be) or a positive 12volt OUT....

I think its a low pressure switch, it signals the compressors to switch on when the pressure inside the tank drops below a certain PSI

If it is a positive out then where would it hook into? on the load wire from the switch?

i dont right now....

you are asking for the model number to the pressure switch right? its only one on top of the tank

and there are 2 toggle switches in between all of it.

the pressure switch is adjustable by the "cap" of it, it rotates in and out like a top

Yes, just the pressure switch.

Are you positive the three leads are +,-, and signal? 

Is it possible that they are C, NO, NC?  (common, normally open, normally closed)  Unless it is an electronic pressure sensor I can't see there being a + and -.  I've never seen an electronic pressure switch that is controlled by twisting the top - those are typically mechanical and have a set of NO/NC contacts.

Now, please keep in mind that I've never messed with air bag stuff, so I may be totally off base here.

I'm positive that its a +    -     and a signal....

heres a pic of it, its the round thing at the top, thats grounded to the back of the metal plate